People gather on the Place de la Republique (Republic Square) in Paris during a Unity rally Marche Republicaine (Picture: AFP PHOTO / BERTRAND GUAYBERTRAND GUAY/AFP/Getty Images)

Paris has today witnessed close to 1.5 million people marching together in defiance of the terrorist attacks that left 17 dead in three days of horrific bloodshed.

The streets of Paris were packed with members of the public, as well as politicians and the family members of victims in what has been called the Paris Unity March, or the March of Unity.

As the march commence world leaders could be seen walking arm-in-arm in a display of peace and unity.

Behind them the crowd of demonstrators filled over side street and alley for over two kilometres as the people of Paris demonstrate they will not bow to terrorism.

Marchers have been breaking in spontaneous rounds of applause and cheering, as well as renditions of the French national anthem as the crowd has started making its way from the historic Place de la Republique to Place de la Nation.

Family members of those killed take part in a Unity rally Marche Republicaine today in Paris (Picture: AFP PHOTO / ERIC FEFERBERGERIC FEFERBERG/AFP/Getty Images)

Even as night falls the crowd remains in place to send a message to the people who attacked their city and their people (Picture: REUTERS/Yves Herman)

People watch from their roof-top apartment as some thousands of people gather at Republique square in Paris today (Picture: AP Photo/Peter Dejong)

David Cameron is also attending the march with several other world leaders including Angela Merkel and Israeli Prime Minister Benjamin Netanyahu.

Far from being a nationalistic demonstration, the crowd reportedly contains people from every corner of French society, with a separate march taking place in Marseille – the city with the largest Muslim population in France.

Many of the demonstrators took the march as an opportunity to show they have not allowed the attacks scare them, with a several people holding signs containing the words ‘not afraid’.

Lassina Traore, a 34-year-old French-born Muslim from the Ivory Coast, said the march is ‘a real sign of how strong France is. It shows that France is strong when she is united against these people’.

The streets of Paris were packed full of demonstrators with a common cause (Picture: Dan Kitwood/Getty Images)

Several flags and messages of tolerance were waved during the demonstration (Picture: AFP PHOTO / LOIC VENANCELOIC VENANCE/AFP/Getty Images)

It is estimated that Paris has never seen crowds of this size before (Picture: AFP PHOTO / JEAN-FRANCOIS MONIERJEAN-FRANCOIS MONIER/AFP/Getty Images)

Thousands of people took to the streets in Berlin in a separate demonstration in support of the French people following the terrorist attacks.

Other demonstrations were seen in Trafalgar Square in central London as thousands came together to both pay respects tot he victims of the attacks and stand in defiance against terrorism.

The actions of the French people today stands in stark contrast with the shocked silence Paris, and indeed the world experienced in the days following the attacks.

Italian football team Lazio also showed their support for the people of France by wearing shift emblazoned with the phrase ‘Je Suis Charlie’ during their match against AS Roma today.

A woman holds a giant pencil with the words “Je suis Charlie” (I am Charlie) during a silent protest for the victims of the shooting at the Paris offices of weekly newspaper Charlie Hebdo, at the Pariser Platz square in Berlin January (Picture: REUTERS/Hannibal Hanschke)

(Picture: Dan Kitwood/Getty Images)

Despite the march quickly being hailed as one of the most significant events in France’s recent history, some unexpected turns were bound to be taken.

One such was Danish Prime Minister Helle Thorning-Schmidt falling over as she left the Elysee Palace.

Aides were quick to help Ms Thorning-Schmidt back to her feet (Picture: Thierry Chesnot/Getty Images)

Emotions ran high in the grieving City of Light, with many of those marching bursting into tears as they came together under the banner of freedom of speech and liberty after France’s worst terrorist bloodbath in more than half a century.

On the streets, many came with their families. Jean-Alain said he brought his seven-year-old son Alessandro with him ‘so it’s more concrete for him, so that he can see that we all think the same thing.’

‘The people who pick up a gun and kill people are cowards,’ the 39-year-old gently explained to his boy.

Despite this, one person taking part in the march told BBC News that there is a ‘light and happy’ mood within the demonstration, with many people holding humourous placards, such as a young man who held a sign which read: ‘I am Muslin: Don’t panic.’

Thousands of people began filling Franceís iconic Republique plaza, and world leaders converged on Paris in a rally of defiance and sorrow on Sunday to honour the 17 victims of three days of bloodshed that left France on alert for more violence (Picture: AP Photo/Peter Dejong)

A person adds to a collection of pens and pencils laid in a circle around “I am Charlie” posters and other tributes ahead of a memorial gathering in Trafalgar Square, London (Picture: AP Photo/Tim Ireland)

Members of the march could be heard chanting ‘Charlie’ – a reference to the attacks on satirical magazine Charlie Hebdo in which gunmen murdered 11 staff members in their Paris offices.

Despite the sense of unity and defiance, police are still on high alert, with 5,500 officers reportedly patrolling the streets of Paris.